In a thermal printer, a color print is formed by depositing dye onto a receiver. The dye is typically deposited one color at a time onto the receiver in an overlaid fashion by first depositing yellow, followed by magenta, and followed by cyan. The quality of a print includes how well the individual colors are aligned on the receiver. In other words, if each of the colors is deposited exactly directly on top of the other, there is high print quality. If, on the other hand, the colors are not perfectly aligned, even by a small increment, the image is not lists clearest and print quality is lost. Print quality is a concern with all thermal printers, even drum printers where the receiver is fixed to one drum and rotates three times to receive the yellow, magenta and cyan dye.
In a scanning thermal dye printer, the image source may pass through three scanning stations, one for each of the yellow, magenta and cyan colors. It is desirable that the finished print have colors matching the input image as closely as possible. It is known that a color image can e separated into the primary colors, but that such color separation may be a complicated procedure and may not exactly produce the colors desired. It is desirable to have a simple, inexpensive apparatus for separating the colors in the input image. Accordingly, it will be appreciated, that it would be highly desirable, to have a filter assembly for controlling the light components and achieving color balance.